Lifting-jack.



G. M. MARKHAM.

LIPTING JACK.

APPLICATION IILED 001?. 4. 1912.

1,081,243. Patented Dec.9,1913.

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CHARLES M. MARKHJ-lll/l', Oh DIEGO, CALIFORNIA.

LIFTINGJAGK,

Specification of Letters Patent. Application filed October 4, 1912.

respondingly grooved rib of rocker member 7. Bifurcated lugs 8 and 9, on opposite ends of the rocker, have links 10 and 11, respectively conne .:ted thereto, link member 10, being a relatively short, and link member 11, a relatively long link member. The said link members have pivoted thereto gripping levers and 13 which have openings lland 15, extending obliquely therethrough. Loops 16, are ada gited to receive a handle or operating bar 1'7, whereby an oscillating motion. may be given to the rocker, and thereby cause the alternate release of gripping levers 12 and 13, which, upon their release, will drop down, and again grip the central movable member 41-. l Vhile one gripping lever is lifting the central member on the upward motion of the corresponding end of the rocker, the opposite gripping lever is released to obtain a. new grip on member l. Links 18 connect the rocker to table member 3.

To lower the device with a weight or load on the support, rocker i", has pivoted thereto releasing levers 19, having their inner extremities extending beneath gripping levers 12 and 13, and their outer extremities 20, extending from one side of the rocker.

1,081,243, lhatented Dec. 9, 1913.

Serial No. 723,867.

To aZZ 'w/wm 2'25 may concern e it known that l, Crrannns M. MARK- HAM, a citizen of the United States, residing at San logo, in the county of San Diego and State of California, have invented an Improved Lifting-Jack, of which the follow 6, on the bottom ing 1s a full and exact description.

My invention comprehends certain new and useful improvements in lifting-jacks, and is designed particularly for use in connection with girder supports for concrete construction forms, and the invention has for its object the provision of a supporting and lifting mechanism which will be simple, durable, and cllicient for jacking up machinery, floor plates, beams, and the like, and which shall have no delicate or finely adjusted elements which would be likely to be affected by contact with, or clogged by accumulations of concrete, dust, or similar substances.

it is a design of the invention that the desired vertical adjustment may be quickly at tained, that the elements of the device or mechanism shall be easily renewable, that the device shall be adapted for a quick release from the completed work or structure to which it has been applied, and that the parts of the device may be disassembled for Loops 521, are adapted to carry operating bar convenience in packing. 17, which normally rests lightly on levers l9, and by operating bar 17, their outer extremities 20, will be alternately depressed, causing the inner extren'iities to lift and re lease gripping levers 12 and 13, whereupon member t will be lowered. 'lhe lifting 'ack may be more quickly released by dcpressing the outer ends of the gripping levers. Central member 4c may have a plate 22, for carrying a load, and the plate may be modified for different uses.

From the foregoing it may be seen that I have provided a lifting jack which may be quickly adjusted and which has no parts which are liable to be affected by concrete. The oscillating motion of the rocker is etleo tive for the intermittent and alternate release of the gripping levers, which, when so released, will drop down and obtain a new grip upon the central supporting member, and lift the same upon their upward movement. The lifting jack will lift heavy weights with but little friction as the several parts operate with an oscillating motion.

he gripping tendency is increased in proportion to the weight or load carried. It will be apparent that I have provided an For performing the functions herein set forth, the device may be embodied in a suitable form of mechanism, a preferred form of which is shown in the accompanying drawings, whcreon-- Figure l is a side elevation of my device with the gripping levers partly in section; 1* ig. 2 is a side elevation of the device with the releasing levers and a portion of the bar which operates them; Fig. 3 is a plan and detail view of the rocker member having the release levers mounted thereon; and Fig. 4 is a transverse sectional and detail view of the rocker, disclosing the relative positions of the gripping lever, the releasing lever therefor, and thebar for operating the same.

In the several views, like reference characters apply to like parts.

My improved device has a standard 1, of steel pipe, having a base flange 2, and a table 3, on the opposite end, is provided with a movable member l, slidable therein and extending from the standard. The table is provided with a rib 5, transversely arranged thereon, and adapted to engage with a cor- 8. In a lifting jack, the combination with a standard having a flanged base member atthe bottom and a flanged table member at the top, of a rib extending transversely on said table member, a rocker having a grooved bottom adapted to engage with said rib and prevent lateral displacement of the rocker, loops on one side of said rocker adapted to receive the operating handle, a detachable handle adapted to be inserted in said loops and operate the rocker, bifurcated members secured to opposite ends of said rocker, links pivotally connected to said bifurcated members, gripping levers pivotally connected to said links and adapted to a limited oscillatingmovement, said gripping levers having obliquely disposed openings in their inner extremities, a central member slidably mounted in said standard and ex,- tending upward therefrom and through-said improved device which may be advantageously employed in concrete construction, although it is not limited to any such use, but is susceptible of various other applications. The device is positive in action and affords considerable leverage so as to render necessary only a limited and minimum exertion on the part of the operator, the device also possessing the characteristics of simplicity, durability, and eiiiciency in construction and operation, and consisting of few parts cheaply manufactured and readily assembled.

I claim as my invention:

1. Ina lifting jack, the combination with a standard having a base and a table member, of a rib extending transversely upon the table member, a rocker engaging with said rib, said rocker being adapted to oscillate upon said rib, loops on said rocker adapted to receive a detachable handle, biopenings in the gripping levers and norfurcated members mounted on opposite ends mally engaging with the edges of said openof said rocker, links pivotally connected ings to lock said central member against a downward movement, and means for releasing said gripping levers comprising release ing levers pivotally mounted on said rocker and having their inner extremities extending upward and beneath said gripping levers and normally resting against them, the said releasing levers having their outer extremities projecting froma side ofthe rocker, elongate loops on the same side of the rocker, and an operating lever adapted to be inserted in said elongate loops and normally rest upon thg outer extremities of the releasing levers, the said releasing levers alternately lifting and thereby disengaging said gripping levers from thecentral mem- 'ber when said operating lever is depressed to actuate the releasing levers, substantially as set forth,

In testimony whereof I have hereunto affixed my signature to the foregoingspecification, this 28th day of September, in the year 1912.

CHARLES M. MARKHAM. In the presence of- F. M. KnnNnY, J. \V. MARTIN.

tosaid bifurcated members, gripping levers connected to said links having-a limited oscillating movement, a central supporting member slidably mounted in and extending from said standard and engaging with said gripping levers, and a handle adapted to be inserted in said loops on the rocker for manually operating the device, substantially as set forth.

2. In a lifting jack the combination of a standard, a base on the lower end thereof, a table on the top end, a rib extending transversely on said table, a rocker operating upon said rib, bifurcated members carried by' the opposite ends of said rocker, links pivoted to said bifurcated members, loop gripping levers carried by said links and having an obliquely extending opening therein, means mounted on each end of said rocker engaging with said gripping levers for releasing same, a central member telescopically mounted in said standard and extending therefrom and engaging with said gripping levers, and a handle mounted in loops on said rocker for manually operating said rocker.

Commissioner of Patents,

. fl/ Copies of this patent may be obtained for five cents each, by addressing the Washington, D. C. 

